Dipstick Blowing Out at High RPM
 

Hey All,

A few weeks ago I had about 1/2 quart TOO much oil in my Road King. While blasting up the express way, the oil cap and dipstick blew out of my bike. I assumed and was told by members on this forum that it was because I had too much oil and that it should not happen if I suck some of that excess oil out (no need as the excess oil was all over the back end of my bike).

Fast forward three weeks, and the oil is measuring half way up the dipstick on a cold engine, full on a warm engine. I was blowing up the side of a large hill, racing through the gears and running at high RPMS. Sure enough, the dipstick blows out again, and oil all over the freshly polished bike.

Now, the only thing that these two scenarios have in common is that on both occassions I was really getting into it and running through the gears at high RPMs. This high RPM condition is obviously building a lot of presure in the crank case and causing the dipstick to blow. The question is why.

Any thoughts. I am thinking that there must be a venting issue somewhere. Any help is appreciated.

breathers
 

check your head breathers,disconnect hoses(or a/c itself)and feel air coming out of breathers.had a bike in the shop doing same thing,the round filters in the acual breathers in the heads where all plogged.only other senario is that rockers where taken off and lower r. box gaskets are on backwards
kirby
www.veetwinperformance.com

Never overlook the stupidly simple either. Is your dip-stick plug in good shape? If it pulls out rather easily, it will certainly blow out too. Before you stick it in, wipe the oil off the plug and wipe out the throat of the fill tube. Turn it around a couple of times after you push it in to get a good seal. It's worth a try as opposed to yanking stuff off your engine.

After many years of thinking about it, doing cost-analysis and having an engineering team on the problem night and day, Harley finally came to the conclusion to make them screw-in.

Thanks guys. The dipstick is definately not easy to pull out, so I am going to have to go with Kirby's suggestion.

Kirby, I pulled the a/c appart and then pulled the breather tubes out. There was some engine oil in bottom of the filter as well as on the backplate. I assume that this is blow by from when I had too much oil. When the engine is fired up, there is a small amount of air coming out of the front breather hole and an even smaller amount coming out of the rear breather hole. Please correct me if I am wrong, but based on what you said, I am thinking that some oil traveled through the filters and has saturated them to the point where there is not enough air flow.

Before I tear off of the rocker covers, could you tell me about how much air I should expect to feel coming out of the breather holes. It was quite minimal, even when I twisted the throttle.

Thanks for your help.

its minimal at low rpm when the rpm increasee the crankcase pressure increases .. when was the build done???
some times too much crankcase pressure can be attributed to needing a new set of rings. too much blow by.
some times taking the rockers off and drilling the holes out a bit so oil and air can flow better will do it . .
try changing the oil and take it on a high speeed run but gradually go up to speed dont hammer it. then try hammering it and see if it does it again. .
also check for any kinks in that rear breather.

The build was only done about 12,000 miles ago, so I doubt it needs needs new piston rings. I plan to take the rocker boxes off this weekend in order to inspect and replace the filters. Do you think that I should just go ahead and drill out the holes at that time. Is there any reason why this would not be a good idea? How big should I drill the holes? How many holes are there to drill?

RKK ill check in the morning on the size but before you go and do that change the oil first. hey ya never know do the easy things first.
Scott from hillside or pro drag might know the size off their head but get the biuke nice and hot then change the oil first.
i know your fustration i am chasing a problem now that is really starting to wear my patience.

Hey SE,

Help me out here please as I am confused. Why would changing the oil possibly decrease the amount of pressure building in my crankcase?

The dipstick doesnt pop every time I hammer it, and I really want to nip this thing in the butt. I was more than 300 miles away from home this past weekend when it decided to pop last time.

I stopped in to a Harley Dealer to ask their opinion. Both the service manager and a tech told me that I just shouldn't hammer it anymore. Can you believe these guys?

When you do an oil change, how much oil are you putting back in?

Steve

I start with 3.5 quarts, run it, and then add as neccessary. Never more than 4 quarts.